Consolidating ballast

ABSTRACT

Ballast beneath a railroad track is consolidated by spraying binder into the ballast in the zones of operation of the tampering and ramming units during operation of the same.

United States Patent 91 Unbehaun et al.

[451 Mar. 11, 1975 CONSOLIDATING BALLAST [75 Inventors: Olaf Unbehaun, Neunkirchen;

Uwe Hampel, Ludwigshafen; Norbert Scholz, Mannheim; Horst Gassmann, Viernheim; Walter Schneider, Ludwigshafen; Heinz Hesser, Hochdorf- Assenheim; Walter Herrmann, Mannheim; Ber-told Bechert, Nurenberg, all of Germany [73] Assignee s;BASF Aktiengesellschaft Ludwigshafen/Rhein and Heinrich Cronau, Building, Contractors, Land Saarland, both of Germany [21] Appl. No.: 472,454

[30] Foreign Application Priority Data May 26, 1973 Germany 2327063 Primary Examiner-Lloyd L. King Assistant Examiner-Randolph A. Reese Attorney, Agent, or Firm-Johnston, Keil, Thompson & Shurtleff [57] ABSTRACT Ballast beneath a railroad track is consolidated by spraying binder into the ballast in the zones of operation of the tampering and ramming units during operation of the same.

7 Claims, No Drawings CONSOLIDATING BALLAST This invention relates to a process for the consolidation of crushed rock ballast, in which said ballast is consolidated by introducing plastics materials and bonded thereby.

ln roadbeds, the ballast has the function of taking up i the static and dynamic forces acting on the rails by the vehicles and of transmitting said forces to the subgrade, the alignment of the track not having to be corrected for long periods of time. These forces increase considerably with increasing speed and axle load of the vehicles, and the stresses on the tracks and ballast increase accordingly, particularly where the track is slightly out of alignment. Unduly large horizontal forces can lead to track distortions and unduly large vertical forces can cause increased settlement of the ties (sleepers) and thus produce what is called out-of-surface track. Increased lateral forces are particularly detrimental in curves which make up for example almost 40 percent of the West German railroad system, and such forces necessitate high resistance to transverse displacement on the part of the ties if adequate safety as regards distortion is to be guaranteed. Particularly detrimental is mixed traffic, i.e., fast passenger trains and slow heavy freight trains, since a compromise must be made when electing the degree of cant of the track in such curves. The centrifugal forces of the fast passenger trains act outwardly, whilst the weight bias of slow freight trains caused by the slope tends to produce an inward displacement of the tracks. This leads to gradual loosening of the ballast and thus to poor alignment.

It is therefore necessary to re-align the tracks by periodic maintenance. Such maintenance is effected by means of large machines, e.g. track leveling and tamping machines, which are moved along the track and use mechanical means such as tampers to consolidate the ballast near the ties and particularly beneath the ties by tamping and/or vibration. Tamping of the ballast may be completed by means of machines for ramming the shoulders and tamping the cribs. When the tampers are removed from the ballast, slight loosening of the latter occurs, this being rectified by traffic only after a period of time. Maintenance intervals depend on the subgrade, the amount of traffic, and the proportions of the various types of traffic. Thus the railroad authorities are interested in a process ensuring accurate track alignment over a long period without subsequent adjustment thereof being made impossible.

The report Stabilized Ballast Investigation of the Office of High-Speed Ground Transportation, U.S. Department of Transportation, Contract No. 3-0254 describes a process for consolidating ballast in which the ballast is first washed and then sprayed with a 1 percent ammonia solution followed by an aqueous dispersion of a butadiene/styrene copolymer. After the ballast has dried, the ties and rails are placed on the ballast and the whole is again washed with ammonia solution and resprayed with aqueous dispersions of butadiene/styrene copolymer. One drawback of this. process is that it is virtually only usable on new tracks or on old tracks only after lifting the track. If this process is used in the periodic maintenance of existing tracks, none of the bonding agents reaches the important load-bearing zones of the ballast beneath the ties. Furthermore, the

butadiene/styrene copolymers used in this process have a marked tendency to age.

German Published Application No. 2,063,727 also describes a process for stabilizing ballast, in which the ballast is coated with a binder, completely or partially, particularly at the points of contact. This binder is in- 5 jected into the ballast and fills up the voids on curing,

with or without the formation of a foam. However, said application does not disclose the plastics materials to be used in said process, nor does it reveal how said materials are to be injected into the ballast. German Published Application No. 2,063,727 does not therefore give a reproducible teaching as to how to use the invention.

We have now found that ballast may be consolidated by introducing binders for bonding the rock ballast, this being advantageously effected by spraying the binder into the ballast in the zones of operation of the tamping and ramming units during tamping and/or ramming. A particularly advantageous method of spraying the binders into the ballast involves the use of nozzles mounted on said units, e.g. the tamping and/or ramming units, and adapted to receive said liquid binders via lines specially provided inside said units. For example, the aqueous dispersion or other liquid binder may be advantageously injected through the tampers of tamping machines, frequently from 60 to percent of said tampers being advantageously provided with one or two nozzles. Such machines usually have at least four and frequently eight or more, e.g. 32 or 34, tampers. Advantageously, the binders are sprayed into the ballast laterally from the tampers of such machines as they move down into the ballast, such spraying being effected by means of nozzles mounted at the sides of the tampers and connected to feed lines passing through the interior of the tampers. The direction of spraying is such that the binder preferentially reaches the zones at the sides of and beneath the ties. The binders may be forced through the feed lines for example either by compressed air or by means of a pump. This operation may be similarly carried out when using crib tamping machines, in which a plurality of nozzles, usually from eight to 20 nozzles, may be mounted at the sides and/or on the base, through which nozzles a polymer dispersion may be sprayed into the zone being tamped, that is, in particular, toward the areas at the sides of and beneath the ties. If packing is carried out using shoulder ramming machines, the binders may be advantageously sprayed onto the ballast through nozzles mounted on the side facing the ballast, spraying being commenced when the nozzles have reached a distance from the surface of the ballast of from about 5 to 20 cm and in particular from 5 to 10 cm, or spraying may not be commenced until the said tamping surface is in contact with the ballast.

Suitable binders are, for example, those based on bitumen and, preferably, aqueous polymer dispersions. Aqueous polymer dispersions which may be used are for example commercially available dispersions based on polyacrylates and/or vinyl ester polymers and/or polyisobutylene.

Suitable aqueous dispersions contain plastics of the above types generally in amounts of from 20 to 60 percent and in particular of from 40 to 60 percent, by weight of the weight of dispersion. Aqueous dispersions of polymer and preferably of copolymers of acrylates and/or methacrylates with C and particularly C alkanols, particularly acrylates and/or methacrylates of ethanol, n-butanol, isobutyl alcohol, iso-octanol and 2-ethylhexy1 alcohol have been found to be particularly useful. The content of acrylates and/or methacrylates of the above kinds in said emulsion copolymers is generally from 30 to 90 percent by weight, based on the weight of polymer. Such copolymers usually also contain vinyl esters such as vinyl acetate and/or vinyl propionate, vinyl aromatic compounds such as, in particular, styrene, and/or acrylonitrile, and also minor quantities, usually of from 1 to 10 percent and in particular of from 2 to 5 percent by weight, based on the polymer, of preferably C monoand/or di-carboxylic acids and/or their amides, particularly acrylic acid, methacrylic acid, fumaric acid, methacrylamide and acrylamide. The amount of vinyl acetate and/or styrene in such copolymers is usually in the range of from 30 to 60 percent by weight, whilst the amount of acrylonitrile generally ranges from 5 to 20 percent by weight, based on the polymer. In some cases, vinyl chloride is also suitable as comonomer for the copolymer, this being used in amounts of from 20 to 50 percent by weight, based on polymer. In addition to or in admixture with said polyacrylates of the above kinds, aqueous vinyl ester copolymers, particularly those derived from excess amounts of vinyl acetate or vinyl propionate, may be advantageously used. Such copolymers usually contain amounts of from about to 30 percent by weight, based on copolymer, of acrylates of C alkanols and- /or vinyl chloride in the form of polymerized units. Other interesting polymer dispersions are aqueous dispersions of polyisobutylene containing polyisobutylene having a molecular weight of from 5,000 to 200,000 and in particular of from 10,000 to 130,000, as measured by the Staudinger method described in Die hochmolekularen organischen Verbindungen, Springer-Verlag, Berlin 1932, pp. 170 et seq., in amounts of from to 60 percent by weight, based on the dispersion. Such polyisobutylene dispersions, which may be prepared in known manner as secondary dispersions i.e., by dispersion high molecular weight polyisobutylene in water with the addition of dispersing agents, may be used alone or in admixture with polyacrylate dispersions of the above kinds. Where polyacrylate dispersions of the above kinds are used in admixture with polyvinyl ester dispersions and/or polyisobutylene dispersions, the ratio of polyacrylate (solid) as one component to polyvinyl ester (solid) and/or polyisobutylene (solid) as the other component is generally from 1:9 to 9:1 and a ratio of from 1:05 to 0.5:] is particular interest. Other suitable polymer dispersions are aqueous dispersions of copolymers of vinyl chloride usually containing from 10 to 40 percent by weight of polymerized units of acrylates with, usually, C alkanols.

The polymer dispersions of the above kinds may be prepared in conventional manner using conventional emulsifiers and dispersing agents and the usual catalyst and, if necessary, chain stoppers.

The amount of plastics material used in aqueous dispersion for bonding the ballast is usually from 1 to 10 kg of plastics (solid) per tie. This amount is preferably distributed over from 10 to 100 nozzles mounted on the tamping and ramming tools.

Suitable bitumens are for example aqueous bitumen dispersions and bitumen melts and also bitumen solutions, these being generally obtained from bitumen B 40 to B 200 or from blown bitumen which may contain adhesion-promoting additives and/or wetting agents.

The process of the invention makes it possible to consolidate ballast, particularly as used in roadbed construction, in a very economical and durable manner, with the result that the time between successive realignments of the tracks and consolidations of the ballast is substantially longer than has been the case using previous processes. Renewed tamping and consolidation of the ballast is not prevented by the process of the invention, as the original bond is destroyed by the use of the tamping and ramming units.

The following mixtures have proved particularly useful for consolidating ballast by our novel process:

a. from 30 to parts by weight of a,. an approximately 50 percent aqueous dispersion of a copolymer of approximately equal parts of n-butyl acrylate, vinyl acetate and vinyl chloride or a a copolymer of from 80 to 92 percent by weight of iso-octyl acrylate, from 7 to 17 percent by weight of acrylonitrile and from 1 to 3 percent by weight of a C carboxylic acid, i.e., a monoor di-carboxylic acid such as acrylic acid, methacrylic acid or itaconic acid or a a copolymer of approximately equal parts of styrene and an acrylate containing from two to four carbon atoms in the alcohol radical and from I to 4 percent by weight of acrylic acid, with b. from 20 to 60 parts by weight of b,. a 10-60 percent w/w aqueous dispersion of polyisobutylene having a molecular weight of from 50,000 to 200,000 or b a 30-50 percent w/w aqueous dispersion of a copolymer of from 60 to 80 percent of vinyl propionate and from 40 to 20 percent of vinyl chloride or b;,. a mixture of (b,) and (b We claim:

1. A process for consolidating ballast in railroad track, wherein the ballast is tamped and rammed by mechanical means and, during the tamping and ramming operations, a binder for the ballast is sprayed into said ballast in liquid form in the zones of operation of said mechanical means.

2. A process as claimed in claim 1, wherein the binder used is an aqueous polymer dispersion.

3. A process as claimed in claim 2, wherein the aqueous polymer dispersion contains at least one copolymer of an acrylate or methacrylate with a C alkanol.

4. A process as claimed in claim 3, wherein the aqueous polymer dispersion substantially contains a. from 30 to 80 parts by weight of al an approx. 50 percent aqueous dispersion of a copolymer of approximately equal parts of nbutyl acrylate, vinyl acetate and vinyl chloride or a a copolymer of from 80 to 92 percent by weight of iso-octyl acrylate, from 7 to 17 percent by weight of acrylonitrile and from 1 to 3 percent by weight of a C a,fl-olefinically unsaturated carboxylic acid or a a copolymer of approx. equal parts of styrene and an acrylate containing from two to four carbon atoms in the alcohol radical with from I to 4 percent by weight of acrylic acid and b. from 20 to 60 parts by weight of b a 10-60 percent w/w aqueous dispersion of polyisobutylene having a molecular weight of from 50,000 to 200,000 or binder used is bitumen in a molten, dispersed or dissolved form.

7. A process as claimed in claim 1, wherein the liquid binder is sprayed into the ballast through nozzles which are mounted to said mechanical means for tamping and ramming and which are fed with binder through lines provided within said mechanical means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,869,988

DATED March 11, 1975 INVENTORIS) UNBEHAUN et al [I is ceitxfied that error appears m the GDOV-III8HHIIEG patent and that said Lefieas Patent are hereby conected as shown bEiOWl In the Abstract, Line 3, delete "tampering" and insert--tamping-- Signed and Scaled this eleventh Day of May1976 [SEAL] A new:

RUTH C. MASON tlllvslmg Officer C. MARSHALL DANN (mnmisximu'r uflarcnls and Trademarks 

1. A process for consolidating ballast in railroad track, wherein the ballast is tamped and rammed by mechanical means and, during the tamping and ramming operations, a binder for the ballast is sprayed into said ballast in liquid form in the zones of operation of said mechanical means.
 1. A process for consolidating ballast in railroad track, wherein the ballast is tamped and rammed by mechanical means and, during the tamping and ramming operations, a binder for the ballast is sprayed into said ballast in liquid form in the zones of operation of said mechanical means.
 2. A process as claimed in claim 1, wherein the binder used is an aqueous polymer dispersion.
 3. A process as claimed in claim 2, wherein the aqueous polymer dispersion contains at least one copolymer of an acrylate or methacrylate with a C1-12 alkanol.
 4. A process as claimed in claim 3, wherein the aqueous polymer dispersion substantially contains a. from 30 to 80 parts by weight of a1. an approx. 50 percent aqueous dispersion of a copolymer of approximately equal parts of n-butyl acrylate, vinyl acetate and vinyl chloride or a2. a copolymer of from 80 to 92 percent by weight of iso-octyl acrylate, from 7 to 17 percent by weight of acrylonitrile and from 1 to 3 percent by weight of a C3-5 Alpha , Beta -olefinically unsaturated carboxylic acid or a3. a copolymer of approx. equal parts of styrene and an acrylate containing from two to four carbon atoms in the alcohol radical with from 1 to 4 percent by weight of acrylic acid and b. from 20 to 60 parts by weight of b1. a 10-60 percent w/w aqueous dispersion of polyisobutylene having a molecular weight of from 50,000 to 200,000 or b2. a 30-50 percent w/w aqueous dispersion of a copolymer of from 60 to 80 percent of vinyl propionate and from 40 to 20 percent of vinyl chloride or b3. a mixture of (b1) and (b2).
 5. A process as claimed in claim 2, wherein the aqueous polymer dispersion contains polyisobutylene.
 6. A process as claimed in claim 1, wherein the binder used is bitumen in a molten, dispersed or dissolved form. 